Search Publications
Starcounts Redivivus II: Deep Starcounts With Keck and HST and the Luminosity Function of the Galactic Halo
Smail, Ian; Thompson, Ian; Yan, Lin +2 more
We have combined deep starcount data with Galaxy model predictions to investigate how effectively such measurements probe the faint end of the halo luminosity function. We have tested a number of star/galaxy classification techniques using images taken in 0.5 arcsec seeing with LRIS on the Keck telescope, and we find that different combinations of…
The Inscrutable Hot Component in the Symbiotic Binary Z Andromedae
Mikolajewska, Joanna; Kenyon, Scott. J.
We analyze optical and ultraviolet spectroscopic observations of the symbiotic binary star Z Andromedae. This system consists of an M3 -M4 giant and a hot component surrounded by an ionized nebula. The orbital mass function is consistent with Mg∼Msun and Msunh∼0.5-1 Msun as in other…
Globular Cluster Photometry With the Hubble Space Telescope. V. WFPC Study of M15's Central density Cusp
Schneider, Donald P.; Yanny, Brian; Bahcall, John N. +1 more
We describe images of the center of the dense globular cluster M15 (NGC 7078) obtained with the Hubble Space Telescope Wide Field and Planetary Camera 2 (WFPC2). Data taken in the F336W, F439W, and F555W filters (approximately U, B, and V) are used to study the surface density distribution of the ∼3×104 stars detected in a 5 arcmin…
The Flagstaff Astrometric Scanning Transit Telescope (FASTT) and Star Positions Determined in the Extragalactic Reference Frame
Monet, Alice K. B.; Monet, David G.; Stone, Ronald C. +2 more
This paper describes the methods used for determining star positions in the extragalactic reference frame with the Flagstaff astrometric scanning transit telescope (FASTT) from drift scan observations. A laser metrology system is used to correct for instrumental motions, and detailed numerical computations are made for atmospheric and room refract…
Hubble Space Telescope Observations of Oxygen-Rich Supernova Remnants in the Magellanic Cloud. I. Narrow-Band Imaging of N132D in the LMC
Kirshner, R. P.; Raymond, J. C.; Long, K. S. +6 more
We present Hubble Space Telescope (HST WFPC2 images of the young, oxygen- rich supernova remnant N132D in the Large Magellanic Cloud in the [O III]λ5007, [O II]λ3727 and [S II]λλ6724 emission lines, plus a visible continuum band. The ~0.1" resolution of HST allows us to analyze structure within N132D at scales comparable to ground-based images of …
WFPC2 Observations of Star Clusters in the Magellanic Clouds. I. The Large Magellanic Cloud Globular Cluster Hodge 11
Fall, S. Michael; Rich, R. Michael; Mighell, Kenneth J. +1 more
We present our analysis of Hubble Space Telescope Wide Field Planetary Camera 2 observations in F555W (broadband V) and F450W (broadband B) of the globular cluster Hodge Il in the Large Magellanic Cloud galaxy. The resulting V vs B - V color-magnitude diagram reaches 2.4 mag below the main-sequence turnoff (which is at V_TO_ = 22.65+/-0.10 mag or …
Hubble Space Telescope Observations of Globular Clusters in M31. II. Structural Parameters
Holtzman, J. A.; Faber, S. M.; Grillmair, C. J. +5 more
We analyze post-refurbishment Hubble Space Telescope images of four globular clusters in M31. The ability to resolve stars to below the horizontal branch permits us to use star counts to extend the surface brightness profiles determined using aperture photometry to almost 5 orders of magnitude below the central surface density. Three of the result…
The Ultraviolet Spectrum of the Liner NGC 4579
Filippenko, A. V.; Ho, L. C.; Reichert, G. A. +4 more
We present a Hubble Space Telescope ultraviolet spectrum of the LINER nucleus of NGC 4579, spanning the wavelength range 1160-3270 A. The data reveal a low-excitation spectrum of narrow (FWHM ~1200 km s^-1^) and broad (FWHM ~ 6600 km s^-1^) emission lines, which provide new diagnostics of the physical conditions within the emission-line regions. A…
The Metallicity Dependence of the Stellar Luminosity and Initial Mass Function: HST Observations of Open and Globular Clusters
Tanvir, Nial; Gilmore, Gerard; von Hippel, Ted +2 more
Using HST and the WFPC2 we have acquired very deep V- and I-band photometry of stars in NGC 2420 and NGC 2477 to study cluster luminosity functions at approximately solar metallicity. We have determined these cluster luminosity functions down to M1=10.5(0.2 Msun) and find that the luminosity function of NGC 2420 turns over at…
AO 0235 + 164 and Surrounding Field: Surprising HST Results
Cohen, Ross D.; Burbidge, E. M.; Lyons, R. W. +2 more
Results obtained with the Hubble Space Telescope on the highly variable radio, x-ray, and γ-ray emitting QSO (or BL Lac object) AO 0235+164 are presented and analyzed. WFPC2 images were obtained in 1994 June, when AO 0235+164 was bright (m ~ 17), and the results are described in Sec. 3. After subtraction of the PSF of the QSO, hereafter called AO …